Chapter 21 (Chemistry)

Co3+ (aq) + Cu (s) → Co2+ (aq) + Cu+ (aq) Calculate the standard cell potential for the reaction above given the following information: Co3+ (aq) + e- → Co2+ (aq); Eo = 1.842 V Cu+ (aq) + e- → Cu (s); Eo = 0.521 V

+ 1.321V

A standard electrochemical cell is constructed from an anode that has a standard reduction potential of -2.0 V and a cathode that has a standard reduction potential of +0.5 V. Which of the following is the correct expression to calculate the standard cell potential?

+0.5 + 2.0

Given that the standard potential for the half-reaction Ag+ (aq) + e- → Ag (s) is +0.80 V, calculate the standard reduction potential for the half-reaction 2Ag+ (aq) + 2e- → 2Ag (s).

+0.80 V

Co3+ (aq) + Cu (s) → Co2+ (aq) + Cu+ (aq) Calculate the standard cell potential for the reaction above given the following information: Co3+ (aq) + e- → Co2+ (aq); Eo = 1.842 V Cu+ (aq) + e- → Cu (s); Eo = 0.521 V

+1.321V

Which of the following statements correctly describe standard electrode potentials? In what way must half-reactions and/or electrode potentials be manipulated when writing a balanced equation for a redox reaction?

- By convention, standard electrode potentials are quoted as reduction potentials. - The half-reaction for the anode must be reversed when writing the balanced equation for the overall reaction.

Which of the following statements correctly describe tabulated standard electrode potentials? Select all that apply.

- The best oxidizing agents will be reactants in half-reactions with the most positive cell potentials. - If Eo for a given half-reaction is large and positive, the reaction is spontaneous from left to right as written.

Fe (s) + Hg22+ (aq) → Fe2+ (aq) + 2Hg (l); Eo = 1.229 V Hg22+ (aq) + 2e- → 2Hg (l); Eo = +0.789 V Using the standard cell potential given above and the standard reduction potential listed above, calculate the standard reduction potential for the half-reaction Fe2+ (aq) + 2e- → Fe (s).

-0.440V

Given that the standard potential for the half-reaction Ca2+ (aq) + 2e- → Ca (s) is -2.87 V, what is the standard potential for the half-reaction 2Ca2+ (aq) + 4e- → 2 Ca (s)?

-2.87 V

Ca (s) + Mg2+ (aq) → Ca2+ (aq) + Mg (s); Eocell = 0.50 V Mg2+ (aq) + 2e- → Mg (s); Eomagnesium = -2.37 V Using the standard cell potential given above and the standard reduction potential listed above, calculate the reduction potential of the half-reaction Ca2+ (aq) + 2e- → Ca (s).

-2.87V

The cell potential for the standard hydrogen electrode (SHE) is by definition equal to _______ and is used as the reference for other half-cells.

0.00 V

Which of the following electrochemical reactions are spontaneous under standard conditions? Select all that apply

1. 2Cr (s) + 3Sn4+ (aq) → 2Cr3+ (aq) + 3Sn2+ (aq); Ecello = 0.89 V 2. 2Co (s) + 3Cl2 (g) → 2CoCl3 (aq); Ecello = 1.6 V

Ag+ (aq) + e- → Ag (s); Eo = +0.799 V Co2+ (aq) + 2e- → Co (s); Eo = -0.277 V Fe2+ (aq) + 2e- → Fe (s); Eo = -0.440 V Rank the species in order of increasing strength to act as an reducing agent from weakest at the top of the list to strongest at the bottom of the list.

1. Ag (s) 2. Co (s) 3. Fe (s)

Click and drag on elements in order K+ (aq) + e- → K (s); Eo = -2.925 V Hg2+ (aq) + 2e- → Hg (l); Eo = +0.854 V I2 (s) + 2e- → 2I- (aq); Eo = +0.536 V Rank the species in order of increasing strength to act as an oxidizing agent from weakest at the top of the list to strongest at the bottom of the list.

1. K+ (aq) 2. I2 (s) 3. Hg 2+ (aq)

If we were to solve for the cell potential of the following reaction, which two reactions would we first need to find in a standard reduction table? 2Ag+ (aq) + Zn (s) → 2Ag (s) + Zn2+ (aq)

1. Zn2+ (aq) + 2e- → Zn (s) 2. Ag+ (aq) + e- → Ag (s)

Given the following reaction, classify each species according to its ability to act as an oxidizing or reducing agent. Ni2+ (aq) + 2e- → Ni (s) 1. Ni2+ (aq) 2. Ni (s)

1. oxidizing agent 2. reducing agent

Given that the redox reaction for the reaction Fe (s) + 2Ag+ (aq) → Fe2+ (aq) + Ag (s) occurs spontaneously as written, match each species with the appropriate identification. 1. Fe (s) 2. Ag+ (aq) 3. Fe2+ (aq) 4. Ag (s)

1. stronger reducing agent 2. stronger oxidizing agent 3. weaker oxidizing agent 4. weaker reducing agent

Which of the following options correctly describe the units used to express electrical potential, charge, and electrical energy? Select all that apply.

1. the volt is the unit for electrical potential 2. electrical energy can be measure in joules

What is the spontaneous reaction that occurs when the following half-cells are combined? Zn2+ (aq) + 2e- → Zn (s); Eo = -0.76 V Na+ (aq) + e- → Na (s); Eo = -2.71 V

2Na (s) + Zn2+ (aq) → 2Na+ (aq) + Zn (s)

What is the spontaneous reaction that occurs when the two half-cells below are combined? Fe3+ (aq) + e- → Fe2+ (aq); Eo = 0.77 V Ag+ (aq) + e- → Ag (s); Eo = 0.80 V

Ag+ (aq) + Fe2+ (aq) → Ag (s) + Fe3+ (aq)

The cell potential for the standard hydrogen electrode (SHE) is by definition equal to _______ volts. If this half-cell is used as the anode and all of the substances in the cathode are under standard conditions, then the potential of the cell is equal to the standard ______ potential of the cathode.

Blank 1: 0.00 Blank 2: reduction

The standard cell potential may be solved using the equation E^o _______ - E^o ______. Select all the options that will correctly complete the equation given.

Blank 1: cathode or reduction Blank 2: anode or oxidation

S

Entropy

Which compounds or solutions are in an appropriate state for the measurement of Ecell ^o for the reaction given below? Select all that apply. Cu2+ (aq) + H2 (g) → Cu (s) + 2H+ (aq)

H2 gas at 1 atm 1.0 M Cu2+

q

Heat

Given the two half-reactions below, which reaction will be the reduction reaction in the spontaneous reaction that would occur between them? Cr3+ + 3e- → Cr; Eo = -0.74 V Ni2+ + 2e- → Ni; Eo = -0.28 V

Ni2+ + 2e- → Ni

Ag (s) + Li+ (aq) → Ag+ (aq) + Li (s) Calculate the standard cell potential for the above reaction given the following information: Li+ (aq) + e- → Li (s); Eo = -3.05 V Ag+ (aq) + e- → Ag (s); Eo = 0.799 V

Standard Cell Potential = E^o = E^o cathode (reduction) - E^o anode (oxidation) E^o (-3.05) - E^o (0.799) = -3.849 V

By definition, if one coulomb of charge passes between two electrodes that differ in potential by one volt, one _____ of energy is released. This relationship is correctly express as V = ______/_______.

blank 1: joule blank 2: J blank 3: C

As listed in a table of standard electrode potentials, the reactants are potential ______ agents, while the products of the half-reactions are potential _______ agents.

blank 1: oxidizing blank 2: reducing

A species acts as a(n) ______ if it gains electrons in a half-reaction. Conversely, it could potentially act as a(n) ______ agent if it loses electrons in a half-reaction.

blank 1: oxidizing blank 2: reducing

The measure of energy used in electrochemistry is the cell ______ (Ecell), which is the difference in the electrical potential between two electrodes. A common term for this difference in electrical potential is ______ force or emf.

blank 1: potential blank 2: electromotive

If a substance acts as a strong reducing agent, it will appear on a table of standard reduction potentials as the ______ in a half-reaction with a ______ standard reduction potential.

blank 1: product blank 2: negative

If a substance acts as a strong oxidizing agent, it will appear on a table of standard reduction potentials as the _____ in a half-reaction with a _____ standard reduction potential.

blank 1: reactant blank 2: positive

V

electrochemical potential

H

enthalpy

True or false: For a spontaneous redox reaction, the products are stronger oxidizing and reducing agents than the reactants.

false

E

internal energy

When predicting the spontaneous reaction between two different half-cells, the reaction with the most negative cell potential will be the _____ reaction, while the reaction with the most positive cell potential will be the _____ reaction.

oxidation; reduction

Ecell = 0

reaction is at equilibrium

Ecell < 0

reaction is nonspontaneous

Ecell > 0

reaction is spontaneous

The ______ cell potential (E^o cell) is measure with gases at a pressure of 1 at, solutions at 1 M, and solids or liquids in their pure states.

standard